Objective  Community and diversity of ammonia-oxidizing bacteria in rhizosphere soils of reeds, smooth cordgrasses, and mangroves on the wetlands at Minjiang estuaries were studied.

  Method  Twenty-four rhizosphere soil specimens in different layers on the wetlands were collected in 4 seasons with the multi-point mixed sampling method. Sequence of amoA gene in the specimens was determined by the high-throughput sequencing technology for a bioinformatic analysis on the ammonia-oxidizing bacteria community at the sites.

  Result  A total of 300 527 final tags and 2 794 OTUs were detected in the collected specimens. The OTU-based diversity analysis showed little difference on the Chao index among the reed, smooth cordgrass, and mangrove rhizosphere soils. The Shannon index of the mangrove soil was higher than that of the reed soil, while that of the smooth cordgrass soil being the lowest. The Chao and Shannon indices of the reed and mangrove soils were lowest in spring. There was no apparent pattern on the Chao or Shannon index of the soils in different depths. The taxonomy of many of the ammonia-oxidizing bacteria could not be clearly classified. The dominant phylum of the microbes identified in the soils was Proteobacteria, and Nitrosomonas, Thiobacillus, and Caldimonas being the predominant genera.

  Conclusion  Nitrosomonas presented in most of the rhizosphere soils at the Minjiang estuary wetlands, but Thiobacillus and Caldimonas were dominant in individual soil specimens.